A large and diverse group of organisms, algae are generally categorized as green, brown or red algae. They may occur in fresh or salt water, or any moist habitat, and vary from single-celled organisms to complex forms such as seaweed. Some serve an important role in medicines, cosmetics or industrial uses and others are valued for their nutritional value. However, blooms produced by some types of algae are dangerous to people and animals.

On Lake Champlain, hot weather and pollution have triggered blooms of toxic blue-green algae. The blooms are a near-annual event. But this year, they've reached dangerous levels in Missisquoi Bay. The state Health Department say pets and people should stay out of the affected water. Bedford,a town in Quebec that uses the bay for its water supply says the water is no longer safe to drink and has stopped drawing from the lake.

Mike Winslow, staff scientist for the Lake Champlain Committee, also saw the lake surface littered with dead mollusks. The two possible explanations I can think of is: one, it may be related to a de-oxygenation event, that they didn't have enough oxygen at the bottom of the bay, so they died and floated up. The other possibility is that they may be reacting adversely to algae toxins."

Winslow says there was a similar event on a Cape Cod freshwater pond last year that was later linked to a blue green algae outbreak. The mussel mystery is another sign of the lake's complex, inter-connected ecosystem. The system has been altered by an overload of phosphorus, a nutrient that feeds the algae. The phosphorus comes from sewage plants, farm pollution, and storm water run-off.

1. What causes blue-green algae blooms? Blue-green algae are a natural part of water based ecosystems. They become a problem when nutrients (phosphorus and nitrogen) are present in concentrations above what would occur naturally. Under these conditions, the algae can “bloom,” or grow very quickly to extreme numbers. Although summer heat and calm water do not “cause” blue-green blooms, those additional conditions make algae blooms far more likely because blue-greens are especially adapted to take advantage of hot and calm conditions.

2. Are all algae bad and cause illness? No, algae are a normal part of the ecosystem and many species serve as food for other aquatic creatures. Blue-green algae are a normal part of the environment when they are present in low numbers.

3. Do blue-green algae cause illness in animals? Yes! State veterinarians confirmed that several dogs died in the summer of 2012 from exposure to toxins associated with blue green algae. Pets should not be allowed near the shore where decaying algae may be visible, as the algae may stick to their feet, and, should the dogs lick their paws, they could ingest enough toxin to cause death. Horses are very susceptible to toxins and should not drink water from ponds or lakes with blue-green algae. Children, pets and livestock should not be allowed in or near ponds or lakes with blue-green algae.

4. Where does the “risk” from blue-green algae come from? Many species of blue-green algae produce chemical compounds which are toxic to warm-blooded creatures (people, pets and livestock), and some are toxic to other organisms like fish. The biggest risk to health comes from coming into contact with or ingesting the toxins produced by the algae while engaging in what is called “full body contact” (during swimming, skiing or jet skiing, for example), or from inhaling spray cast up from the water’s surface by recreational activities or by the wind. Blue-green algae can also cause dermatological symptoms with prolonged skin contact with water or wet clothes. Children and pets are most at risk while engaging in recreation in the water because they are more likely to accidently or intentionally swallow lake water. Pets can become ill after being exposed to spray, or even from eating dried algae along the shore or after licking algae from their fur. It is best to keep pets and children far away from exposures and move to safer locations. No antidote exists for any known algal toxin currently. This makes prevention the best option for protecting human and animal health during a bloom.

5. Is there anything I can use to kill blue-green algae in my lake? While there are a number of chemicals marketed to control algae (i.e. algicides, the most common of which is copper sulphate), using these while a bloom is in progress is a poor choice. Once a blue-green algae bloom is present, killing it will cause toxins to be released to the water. While the water may look clearer and inviting for recreation, toxins may still be present in high amounts. Also, use of an algicide is a temporary and symptomatic treatment of the problem as the blooms will likely return in short order (days to a couple weeks). The best approach to reducing or eliminating blue-green blooms in a lake is to make sure excessive nutrients (phosphorus and nitrogen) in runoff are prevented or significantly reduced.

6. What should I do if I accidently get lake water on my skin? Wash thoroughly with soap and water. If rash or other symptoms occur, seek medical attention.

7. Is it safe to go fishing and eat the fish I catch? Where blue-green algae is present, avoid coming in contact with lake water as much as possible. Clean fish discarding entrails and other body parts, and consume only the fillet portion. There have been some studies indicating that consumption of a large number of fish from lakes with high toxin levels, even if the consumption is of fillet only, should be limited.

Read more: http://www.livestrong.com/article/475122-is-algae-dangerous-to-people/#ixzz28pOR2OQc

Source: www.kdheks.gov/.../Harmful_Algae_Blooms_Q_and_A.pdf

Source: http://www.vpr.net/news_detail/91649/blue-green-algae-bloom-at-dangerous-levels-on-lake/

Submitted by Conservation Chairman Bill Luther